1. Field of the Invention
This invention relates to a cycle sewing machine which is capable of automatically performing various operations such as disconnecting a main shaft and a drive source, lifting a button holder, and stopping the main shaft of a sewing machine from a drive source thereof, lifting a button holder, and stopping the main shaft just before completion of one sewing cycle for button sewing
2. Prior Art
A sewing machine of this class, which is provided with a stop motion and control device as shown in FIG. 5 has been heretofore well known.
In such a control device, prior to a half stitch when the sewing machine stops, a roller 7 disposed on a lever 6 is rotatably energized to a control disc 5 which is rotated deceleratedly in association with the main shaft 1, and is opposed to a notch 8 in the control disc 5. The lever 6 is rotated from a position shown by a dot-and-dash line of FIG. 5 to a position shown by a solid line thereof with an energizing force or bias of a spring to the lever 6. As the lever 6 is rotated, a stop mechanism (not shown) is actuated to deceleratedly rotate the main shaft 1. At the same time, a rocking lever 3 is swung in response to rotation of an eccentric cam 2 which is secured to the main shaft 1, and an operative end 4 of the rocking lever 3 is in turn so positioned in a position shown by a solid line of FIG. 5 as to correspond to the bottom dead point of a needle.
With the rotation of the lever 6, a connecting lever 10 is moved leftwardly of FIG. 5 by a connecting link 9 integrally supported by the lever 6 to move the lower end of an operative rod 11 coupled to the connecting lever 10 from a position shown by a dot-and-dash line of FIG. 5 to a position shown by a solid line thereof. Consequently, a stepped portion 12 of the operative rod is engaged with the operative end 4 of the rocking lever 3. The rocking lever 3 is moved by a clockwise rotation of the eccentric cam 2 from a position shown by a solid line, corresponding to the bottom dead point of the needle, to the top dead point of the needle. Upon movement of the rocking lever 3, the operative rod 11 is downwardly depressed to thus arrange a button holder means laid on a bed of the sewing machine in a position away upwardly from the bed. Thereafter, the main shaft 1 is allowed to stop by the stop mechanism (not shown).
However, the conventional cycle sewing machine is designed so that the period of time when the main shaft is decelerated until the sewing machine stops corresponds to a half stitch, thereby applying a great impact to the stop mechanism, and possibly damaging the same.
Although attempts have been made to set the timing for fitting of the roller 7 into the recess 8 after one stitch when the sewing machine stops, to afford a longer speed reduction time, the conventional sewing machine involves much difficulty in decelerating the main shaft prior to one stitch since the operative rod 11 interferes with operative end 4 of the rocking lever 3 in the position shown by the dot-and-dash line of FIG. 5.
A provision for affording deceleration of the sewing machine prior to one stitch has been suggested as seen from FIG. 6, wherein like reference characters designate like or corresponding parts in FIG. 5.
The sewing machine as shown in FIG. 6 is fabricated so that the notch 8 in the control disc 5 is formed from an angle at which the disc is rotated, and which corresponds to a point just before one stitch when the sewing machine stops whereas the connecting link 9 and the connecting lever 10 are in turn connected to each other by a slot 9a and a step screw 10a inserted thereinto, the connecting lever 10 being energized by a tension spring 13 when positioned leftwardly in FIG. 6.
In this instance, prior to one stitch when the sewing machine stops, the operative rod 11 tends to abut against the operative end 4 of the rocking lever 3 in the position shown by the dot-and dash line whereas the connecting link 9 is rotated along the slot 9a irrespective of such abutment, to the position shown by the dot-and-dash line so that the lever 6 is rotated to a position shown by a dot-and-dash line where the roller 7 is fitted into the notch 8. This will decelerate the sewing machine before one stitch to apply an impact smaller as compared to the impact upon the stop mechanism when the sewing machines stops as in the case of FIG. 5.
Notwithstanding, the conventional sewing machine as shown in FIG. 6 is unable to obtain a full deceleration capacity when the sewing machine is operated at a high speed so that the impact upon the stop mechanism is not fully relieved. The sufficient deceleration capacity is not expected from the deceleration capacity to the extent that the sewing machine starts its operation prior to one stitch. Needless to say, it is not possible for the conventional cycle sewing machine to start deceleration further prior to one stitch. More specifically, not only commencement of the deceleration but also lift of the button holder and operation of the stop mechanism are effected by the notch 8 in the control disc 5. This results in disadvantages in that when the notch 8 is formed further prior to one stitch, operation of the button holder and the stop mechanism is not well timed, that is, too early to perform a suitable sewing and stop operation. Furthermore, the sewing machine in FIG. 6 is arranged to engage a stepped portion 12 of the operative rod 11 with the operative end 4 of the rocking lever 3 by bias of a spring 13 so that the stepped notch 12 is disengaged from the operative end 4 when any vibration is transferred to the sewing machine, causing malfunction.